textproduct: Albany

WHAT HAS CHANGED

Isolated thunderstorms have been expanded in the forecast this morning across the Lake George Saratoga Region and southern VT based on the elevated convection that developed ahead of the boundary. Temps are in the 30s to around 40F. Impressive 12Z KALY sounding with the deep low-level inversion!

Previous...With wave developing along incoming cold front, chances for precipitation have increased for Thursday morning into the afternoon for areas mainly east of the Hudson River, some of which will be changing to snow.

In addition, higher amounts of snow are now expected across portions of the SW Adirondacks Friday afternoon through Saturday morning in association with clipper system.

KEY MESSAGES

1) The combination of continued snowmelt, moderate to locally heavy rainfall, and possible additional movement of ice and isolated ice jams may lead to some minor river flooding across portions of the southern Adirondacks, Mohawk Valley and upper Hudson Valley today this afternoon through Thursday.

2) Strong storm system and incoming cold front will bring showers and a few non-severe thunderstorms to the region today through tonight, ending as some snow showers on Thursday, along with strong gusty winds in wake of cold front Thursday reaching 35 to 45 mph.

3) Clipper system brings moderate to locally heavy snow across portions of the southern Adirondacks Friday afternoon through Saturday morning, followed by below normal temperatures Saturday afternoon into much of next week.

DISCUSSION

KEY MESSAGE 1...

Cold front has settled to just south of I-90, and should become nearly stationary before gradually lifting back northward this afternoon and tonight. It will be cooler today across the southern Adirondacks/southern VT, mainly in the 40s/50s, however for areas south of I-90, highs will once again reach the 60s for areas near and south of I-90, with some 70s possible once again closer to I-84 across portions of the mid Hudson Valley.

Several clusters of showers and embedded thunderstorms are expected to track eastward for areas mainly near and north of I-90 today into tonight, with occasional extensions passing south of I-90 into the mid Hudson Valley and NW CT. The greatest rainfall amounts are expected across the southwest Adirondacks, especially northern Herkimer and Hamilton counties, where 01Z/NBM 24-hour probs for > 1" ending 8 AM Thursday are 40-60%, with similar probs for >1.5" only ~10-20%. Farther south and east which will be farther from the better upper level forcing, overall rainfall amounts are expected to remain less than 0.50", although locally higher amounts could occur should any showers/thunderstorms linger over any locations.

Continued snowmelt along with moderate to locally heavy rain today into tonight will lead to additional river rises across portions of the southern Adirondacks, Mohawk Valley and upper Hudson Valley. The river rises may also break up lingering ice in these areas, resulting in possible ice jams. Latest NERFC forecasts indicate minor flooding late tonight or Thursday on the Sacandaga @ Hope, the Mohawk River @ Little Falls, West Canada Creek @ Kast Bridge, and also Delta Dam. Several other locations across these regions, as well along the Hoosic and Housatonic Rivers are expected to reach action stage. Trends will need to be watched for overall QPF amounts as well as snowmelt contribution later today into tonight. Should the aforementioned frontal boundary remain farther south with cooler temps persisting across northern areas, overall snowmelt and flooding potential would be less. A Flood Watch is in effect for the southern Adirondacks, Mohawk Valley and upper Hudson Valley for this afternoon through Thursday afternoon.

KEY MESSAGE 2...

Strong cold front will be approaching from the west later today and tonight, and will track eastward across the region late tonight into early Thursday. Several clusters of showers/thunderstorms are expected ahead of the front, especially for areas north of I-90. Latest HREF suggests MU CAPES of 100-250 J/kg this afternoon/evening. Some embedded non-severe thunderstorms will be possible, especially this afternoon/evening.

Although the main cold front shifts south and east of the region shortly after sunrise Thursday morning, approaching upper level trough will be sharpening as it approaches, possibly even becoming negatively tilted. This may allow for precipitation to linger on the cold side of the boundary Thursday morning for areas from Albany south and east, and perhaps into the afternoon across portions of western New England. As colder air builds into the region, precipitation will likely change to snow before ending. There could be some minor accumulations across higher terrain areas of the Berkshires and Litchfield Hills, perhaps a coating up to an inch, with generally a coating on colder surfaces farther north and west extending into portions of the Capital Region.

Strong pressure rises amid cold advection in the wake of the front should allow bring strong gusty winds to the region on Thursday, with the potential for some wind gusts up to 35-45 mph. 01Z/NBM even suggests some gusts over 45 mph possible across portions of the Mohawk Valley, Capital Region and Berkshires once mixing deepens later Thursday morning, and trends will need to be watched for this stronger wind potential and possible need for wind advisory issuances.

KEY MESSAGE 3...

Clipper system approaches from Great Lakes region for Friday into Friday night. Greatest/most persistent forcing looks to be across the SW Adirondacks with this system, bringing light to moderate snowfall, with scattered lighter snow and rain showers farther south and east. 01Z/NBM suggests 24-hr probs ending 8 AM Sunday for >4" snowfall at 70-90%+ across northern/central Herkimer, Hamilton and northern Warren counties, with similar probs for >7" at 30-60%. So, there is some potential for locally heavy snow in some of these areas, especially across the highest elevations Friday afternoon and night which could lead to hazardous travel conditions.

Otherwise, generally below normal temperatures are expected over the weekend into the middle of next week, although a brief period of milder temps is possible Monday ahead of another storm system and strong cold front. Confidence is rather high for well below normal temperatures by next Tuesday-Wednesday, when high temps may struggle to reach the freezing mark in many valleys with 20s across most higher elevations, and overnight lows dropping into the single digits and teens.

AVIATION /14Z WEDNESDAY THROUGH SUNDAY/

We start the TAF period with VFR conditions. MVFR conditions should gradually occur between 15z and 21z with our approaching storm system. Then MVFR conditions continue through the end of the TAF period. Confidence continues to be low on when the rain shower activity begins at KALB, KPSF, and KPOU so continued mention of start timing of shower activity in PROB30 groups for this afternoon into this evening. Between 12/00z and 12/10z, widespread rain should occur during this timeframe.

Winds continue to be calm at KPOU and KPSF, increasing later this morning to light and variable. For KGFL and KALB, northerly to northeasterly winds continue between 5 and 10 knots this morning before transitioning to the west after 12z and continuing through the TAF period to increase by this afternoon. Winds could gust this afternoon into tonight between 20 and 30 knots. LLWS has not been included just yet into the TAFs, but could occur tonight after the 12/06z period for above 2 kft between 50 and 60 knots.

Outlook...

Thursday Night: Low Operational Impact. Breezy. NO SIG WX. Friday: Moderate Operational Impact. Breezy. Chance of RA...SN. Friday Night: Moderate Operational Impact. Breezy. Likely RA...SN. Saturday: Moderate Operational Impact. Windy With Gusts To 33 kts. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Breezy. Chance of RA...SN. Sunday Night: High Operational Impact. Breezy. Definite RA...SN. Monday: High Operational Impact. Breezy. Definite RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Flood Watch from 2 PM EDT this afternoon through Thursday afternoon for NYZ032-033-038-039-041>043-082-083. MA...None. VT...None.